Shimano EW-JC304 Di2 Junction Box

• Shimano Di2 Frame Junction Box
• Connects via SD-300 E-tube wires to four different points: front derailleur, rear derailleur, cockpit junction box and battery mount
• All Di2 components on the bicycle require the same firmware version. Using Di2 components with different firmware versions may cause malfunctions
• Use Di2 system checker to update component firmware
• Number of Ports: 4